The upper chambers of the heart, the atria, have appendages attached to each of them. For example, the left atrial appendage is a feature of all human hearts. The physiologic function of such appendages is not completely understood, but they do act as a filling reservoir during the normal pumping of the heart. The appendages typically protrude from the atria and cover an external portion of the atria. Atrial appendages differ substantially from one to another. For example, one atrial appendage may be configured as a tapered protrusion while another atrial appendage may be configured as a re-entrant, sock-like hole. The inner surface of an appendage is conventionally trabeculated with cords of muscular cardiac tissue traversing its surface with one or multiple lobes.
The atrial appendages appear to be inert while blood is being pumped through them during normal heart function. In other words, the appendages don't appear to have a noticeable effect on blood pumped through them during normal heart function. However, in cases of atrial fibrillation, when the atria go into arrhythmia, blood may pool and thrombose inside of the appendages. Among other things, this can pose a stroke risk when it occurs in the left appendage since the thrombus may be pumped out of the heart and into the cranial circulation once normal sinus rhythm is restored following arrhythmia events.
Historically, appendages have sometimes been modified surgically to reduce the risk imposed by atrial fibrillation. In recent years devices which may be delivered percutaneously into the left atrial appendage have been introduced. The basic function of these devices is to exclude the volume within the appendage with an implant which then allows blood within the appendage to safely thrombose and then to be gradually incorporated into cardiac tissue. This process, coupled with the growth of endothelium over the face of the device, can leave a smooth, endothelialized surface where the appendage is located. In comparison to surgical procedures, devices implanted percutaneously are a less invasive means for addressing the problems associated with the left atrial appendage.
However, due to the wide variability of the ostium size and volume of the left atrial appendage, current implantable devices conventionally include a structure that cannot meet such variability, resulting in inadequate devices for many left atrial appendage anatomies. Further, such implantable devices are substantially limited by the orientation by which they can successfully be deployed. As such it would be advantageous to provide a percutaneous system, method and/or device that addresses, for example, the issues of implant orientation, the variability in sizes and shapes of the left atrial appendage, or all of these, in order to provide high success in left atrial appendage modification. It would also be desirable to provided a device, system and method that enable easy positioning and repositioning of the device relative to the structure being modified or occluded including the positioning (or repositioning) of an occluder portion independent of other components or features of the device.
A variety of features and advantages will be apparent to those of ordinary skill in the art upon reading the description of various embodiments set forth below.